WHAT IS THE JASSM-ER STEALTH MISSILE AND HOW DOES IT WORK?

The 'bunker-busting' JASSM-ER missile is a long-range air-to-surface stealth weapon.

Also known as the AGM-158B joint air-to-surface stand-off missiles, the weapon cruises at subsonic speeds and is GPS-jam resistant.

An infrared imaging system allows it to hit targets with incredible precision, accurate to within as little as 10 feet (three metres), it is reported.

The 'bunker-busting' JASSM-ER missile (file photo) is a long-range air-to-surface stealth weapon. Also known as the AGM-158B joint air-to-surface stand-off missiles, the weapon cruises at subsonic speeds and is GPS-jam resistant

It features a low-profile stealthy design, despite being over four metres (160") long, that makes it almost impossible to detect by anti-missile systems.

The missile can reach targets as far away as 575 miles (925km) - two-and-a-half times the range of the first-generation JASSM.

It uses its inertial navigation and global positioning systems to find its intended target, then its infrared seeker for pinpoint accuracy right before impact, according to the Air Force website.

Designed by US aerospace firm Lockheed and Martin, the missile entered service in 2014, and has a unit cost of £1 million ($1.36 million).

It was fired in combat for the first time in April 2018 when it was used to target chemical weapons plants in Syria by the US military.